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Dolly track width


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#1 Mike Peters

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Posted 29 January 2009 - 10:17 PM

I'm making my own dolly track and would like to first check out the proposed dimensions.

600mm (2 ft) between centers and 50mm (2 in) diameter pipe cut to 1200mm (4 ft) lengths.

I'll also build a rideable dolly platform with 4 rubber wheels and 4 sets of twin in-line pipe wheels (not skateboard config).

Whole setup need to beable to be packed down into a ute or van.

Does anyone see any problems with this size?

I would appreciate any insights.
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#2 Sanjay Sami

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Posted 30 January 2009 - 12:05 AM

Your sizes are wrong if you want to run a proper dolly on it. If you are building your own it should be fine. 2 inch tube diameter seems very excessive, why would you want to use such a thick tube? Also if you are making it you might as well make the track width 62cm (24.5 inches) which is standard width . Maybe Onno can help you out with some advice?
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#3 Mike Peters

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Posted 30 January 2009 - 12:33 AM

Your sizes are wrong if you want to run a proper dolly on it. If you are building your own it should be fine. 2 inch tube diameter seems very excessive, why would you want to use such a thick tube? Also if you are making it you might as well make the track width 62cm (24.5 inches) which is standard width . Maybe Onno can help you out with some advice?


Hi Sanjay

What is the usual outside diameter for the tube is used on track?

Edited by Mike Peters, 30 January 2009 - 12:38 AM.

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#4 Daniel Wallens

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Posted 30 January 2009 - 12:59 AM

What is the usual outside diameter for the tube is used on track?

Generally 1.5"
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#5 Warwick Hempleman

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Posted 30 January 2009 - 03:51 AM

O.D. for dolly tubes is, sadly, a variable. The standard in the US is 1 1/2" (roughly 38mm). There is a lot of 1 1/4" (roughly 32mm) stuff around in Europe, which was Elemack's standard many years ago. There'S also now some 36mm stuff, as it was a standard extrusion one manufacturer chose to use.

Your wheels, if they run on 1 1/2" track, will also work on these smaller diameter tracks, but will have a slightly sloppier fit.

As to track width, you'll have to choose 62cm OR 24 1/2" - there's a tiny but significant difference (24 1/2" =62.23cm).

Make your sections longer, 6' and 8' in addition to one or two 4' and 2' pieces. One of the biggest issues with track is the bump at joints. The less joints, the less bumps. Crosstie spacing is also something to consider, and this is as much a function of how much weight you intend to put on the track (dolly, crane, etc) as anything else. Typical spacing is 60-80 cm.

How do you intend to connect the pieces? Will you make them with fixed crossties or scissoring? Using Stainless, Aluminum, other? Thought about fitting the connecting pins into the rails? Ever plan to make curves? Even in New Zealand, it may be cheaper and quicker to buy the track and still build your dolly.
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#6 Sanjay Sami

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Posted 30 January 2009 - 10:01 AM

Hi Sanjay

What is the usual outside diameter for the tube is used on track?

Warwick is right. There are different diameters, but you will rarely find anything bigger than 1.5"
Dolly track might actually be cheaper to buy than build. Making really good track is a lot more difficult than it may seem.
Warwick is also right about track length . Go with 8 foot lengths for the bulk of it and make one 4 ft and one 2 ft peice.

Regards

Sanjay Sami
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#7 Paul Bruening

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Posted 30 January 2009 - 11:54 AM

A few more tips:

Pipe diameter is gauged by the interior (ID). Tube by the exterior (OD). Stick to tube. There's a common aluminum design by a famous, internet, production educator that uses 2 inch pipe. It's an OK design and easy on the back. But, it is not versatile and requires your own skate to mount any other gear on.

1.5 inches is the most common round tube diameter these days. Yet, square tube is getting more available. That means different load and guide wheel systems. Square tube does allow ground wheels to be the same as track wheels with only the addition of small guide wheels when tracking.

There's two common track widths, at least in the USA: Doorway at 24.5 inch centers and wide at 31.5 (I could be misstating this one, correction is invited) inch centers. There are specialty sizes that usually rent with the applicable dolly. Sorry, I don't know what's happening with track in other countries.

The most usable, versatile and economical size to start with is 1.5 OD, round (I prefer square for my own reasons) steel tube at 24.5 inch centers drilled and lag screwed to notched oak ties (I prefer to weld square stock ties directly to the track) at 7.5 ft lengths that can fit into a van or long-bed pick-up or 4.5 feet for shorter transports. You'll want a loader/ramp section, 2-footer, 3-footer, 4-footer, and as many of the longer ones as you can pull off. I've got two stretches of 20-footers for outdoor work.

Circular track requires a roller-former or bend/jig table and is usually beyond the reach of DIYers. I've never needed anything other than straight track. Circular sections are a pain in the ass to transport, level-up, operate a smooth pan on and coordinate with performers. I think it's only good for retakes and cussing.

The big boggle is the joining system. Commercial track usually has a plug that is mounted in one end of both lines of track. That plug fits into the open end of another section of track. Then, a clamp of some sort keeps the sections pulled together. I use cross-tab plugs for critical alignment. When I manufacture them I weld the end ties at the ends of the track. That lets me butt the track together and run bolts through the ties to keep the sections together. It makes a rock solid join but takes longer to set up than clamps. It's also a cheap way to get the track made and used.

You can just clean the rough parts of the track and wipe the whole thing with oil to keep it from rusting. I've seen it done. But, you have to check it in storage and wipe it often. Plus, it's messy to use. Your grips will look nasty by the end of the day. For a lo-no budger like me who has to set up track and then, sometimes, act in a scene, oiled track is impossible. I paint mine with gloss black, oil based paint. It's a tough paint and retouches well. You have to wire brush (power tools are your friend) every surface and clean completely with a solvent (lots of paper towels for final wipe) to make the paint stick well. You can only paint in passable weather. Painted surfaces take regular retouching, But, it's cheaper than chrome alloys or stainless steel. I slosh solvent through the insides, followed after drying, with paint. If there's already rust inside mix a little gasoline into the paint to make it stick to the rusty parts (of course, do in ventilated place only. Also, solvents and gasoline go "ka-boom") One rainstorm while the gear is strapped to the top of your truck is all it takes to rust up uncoated insides. Prepping the surfaces and painting takes about twice as much time as welding the stuff together. But, you gotta' do it. Paint the insides first. Then the outsides since the new solvent will dissolve the outer paint when you slosh it through.

Or, just use PVC, wood slats and screws. Some folks really love their PVC systems.

Hope that's useful.
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#8 Onno Perdijk

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Posted 30 January 2009 - 03:11 PM

Hello Mike,

As track manufacturer I would suggest not to make your own tracks :-))

Seriously, it all depends where you want to use them for, weather you want curved track and heavier payloads above 80 kg. If so, please contact a manufacturer and deal along. It will cost you a fortune on time and money to make you a perfect set of tracks, especially the joints.

If you want: I can send a sample piece to a friend of mine who lives in New Lynn. Maybe you can take a look at it?

Good luck,

Onno Perdijk
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#9 Ira Ratner

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Posted 30 January 2009 - 05:40 PM

As track manufacturer I would suggest not to make your own tracks :-))


I'm shocked that as a track manufacturer you would say this.
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#10 Mike Peters

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Posted 30 January 2009 - 10:39 PM

Hello Mike,

As track manufacturer I would suggest not to make your own tracks :-))

Seriously, it all depends where you want to use them for, weather you want curved track and heavier payloads above 80 kg. If so, please contact a manufacturer and deal along. It will cost you a fortune on time and money to make you a perfect set of tracks, especially the joints.

If you want: I can send a sample piece to a friend of mine who lives in New Lynn. Maybe you can take a look at it?

Good luck,

Onno Perdijk


Hi Onno,

Thankyou for your kind offer. Yes you are right, sometimes its not worth manufacturing stuff. Luckly, I am a retired engineer/set builder and prefer if possible to make my own gear (its just lots of fun).

It would be silly however to try to make curved track without access to the necessary pipe rollers. So the stuff I do make needs to be standard enough to fit with bought components - hence my enquiry about track standards.

Bush Telly has a production starting in 5 weeks so I have to make 2 m of track next week and a workable dolly for the Director.

Do you have an opinion on aluminium pipe wall thickness? The type of aluminium alloy?

Thanks again for your advice

Edited by Mike Peters, 30 January 2009 - 10:42 PM.

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#11 Mike Peters

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Posted 30 January 2009 - 10:53 PM

The big boggle is the joining system. Commercial track usually has a plug that is mounted in one end of both lines of track. That plug fits into the open end of another section of track. Then, a clamp of some sort keeps the sections pulled together. I use cross-tab plugs for critical alignment. When I manufacture them I weld the end ties at the ends of the track. That lets me butt the track together and run bolts through the ties to keep the sections together. It makes a rock solid join but takes longer to set up than clamps. It's also a cheap way to get the track made and used.


Hi Paul

Thanks for your informative comments and suggestions.

I thought of using some kind of split aluminium or al/composite joiner with 2 grub screws to force the splits apart. However that would mean access to the grub screws from underneath the track which seams like a bit of a pain.

A few more tips:

Pipe diameter is gauged by the interior (ID). Tube by the exterior (OD). Stick to tube. There's a common aluminum design by a famous, internet, production educator that uses 2 inch pipe. It's an OK design and easy on the back. But, it is not versatile and requires your own skate to mount any other gear on.

1.5 inches is the most common round tube diameter these days. Yet, square tube is getting more available. That means different load and guide wheel systems. Square tube does allow ground wheels to be the same as track wheels with only the addition of small guide wheels when tracking.

There's two common track widths, at least in the USA: Doorway at 24.5 inch centers and wide at 31.5 (I could be misstating this one, correction is invited) inch centers. There are specialty sizes that usually rent with the applicable dolly. Sorry, I don't know what's happening with track in other countries.


I'm not sure what standard is in common use in New Zealand. However there are some chapman dollies for hire in Auckland.

Edited by Mike Peters, 30 January 2009 - 10:57 PM.

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#12 Paul Bruening

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Posted 31 January 2009 - 12:20 AM

Hi Paul

Thanks for your informative comments and suggestions.

I thought of using some kind of split aluminium or al/composite joiner with 2 grub screws to force the splits apart. However that would mean access to the grub screws from underneath the track which seams like a bit of a pain.



I'm not sure what standard is in common use in New Zealand. However there are some chapman dollies for hire in Auckland.


Ron Dexter is the guy who made the aluminum track. He reported that it was light and strong enough for a smallish film rig. I can't find the article on a short look-see on his sight. It did take a bigger diameter tube to handle weight and compensate for aluminum's strength limits. He used 6061. Here's a sample of it:

http://www.onlinemet...p...1&top_cat=0

Though, I could get it cheaper from a supplier about an hour from my town.

His dimensions and design can be modified but the tube diameter means you will have to build your own skate and strap whatever dolly onto that. Which, actually, is really handy if you don't know what kind of dollies and tripods you'll end up with from day to day or project to project.

As I say all this, it occurs to me that there is so little track involved in your mentioned project that I'm not sure you'll save enough on the build to justify avoiding just renting. It was only economical for me to take on since I already had the welder and power tools and wanted to build enough sections to see some real savings over rent and purchase. Also, I bought all my steel before the Chinese drove the prices up. I mean, if you just want to build something, then, cool. Since compatibility with existing systems is a plus for you, I'd just copy the design of the system you'll most likely encounter. Most of those systems can be mimicked without too much trouble for a guy like you with experience. The only exotic item from commercial track will be the turned joining pins. Maybe, someone local can knock out a couple sets for you on a small lathe.

One of the down sides of owning your own track is warping. I don't rent mine. Before I built it I spoke to a few guys in the rental biz. They reported warping as one of the reasons for high rental costs. Tracks come back a little warped and have to be adjusted by the maintenance guys. If I don't set mine up and shim it well, it bends and warps ever so slightly. Sure, I can usually bend it back between two posts. But it never goes right back to the original shape. So, it ends up in a permanent, but subtle wonky shape.

As far as the joins' design, they're usually just bar stock turned so that part of the stock fits with a column snugly into the tube and is machine screwed through the tube from below. The joiner has a short collar that is the same dimension as the tube's OD. Then the protruding bit is tapered and rounded so that it easily enters the other tube but has enough column on it to assure a continuous surface from the originating tube, across the collar and onto the next tube. Aluminum would be easier to turn and cheaper than stainless. But I suspect it would wear out too fast to be sensible. That's just opinion. Cromo and stainless are what I've seen on the few examples I've run across.

There's bound to be someone here that can speak better about conventional designs. I'm afraid I'm more useful on doing things in a peculiar but cheap fashion. I would like to hear how your adventure in this unfolds.
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#13 Mike Peters

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Posted 31 January 2009 - 11:37 PM

Hi Pual

Thanks for the tips. I'll do up some drawings and post them here as PDF attachment, plus the finished item.

Make sense to buy the joiners, if they are available somewhere.
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#14 JD Hartman

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Posted 01 February 2009 - 11:13 AM

Aluminum joiners should be fine if you are building the track for your own use. Easy to machine for a tight piston fit. If you are going to make "split dowels" for joiners, put the setscrew or grub screw opening in the top of the rail. Wheels don't ride directly on the top. Or use pull clamps like those made by Carr-Lane, Jergens, Gibralter, etc. to hold two section firmly together. Like these: http://www.carrlane....A3C3B285351465C Obviously the hook would be rotated ninty degrees and used to pull against a stud mounted in the tie of the next section.

Edited by JD Hartman, 01 February 2009 - 11:17 AM.

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#15 Paul Bruening

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Posted 01 February 2009 - 11:28 AM

Aluminum joiners should be fine if you are building the track for your own use. Easy to machine for a tight piston fit. If you are going to make "split dowels" for joiners, put the setscrew or grub screw opening in the top of the rail. Wheels don't ride directly on the top. Or use pull clamps like those made by Carr-Lane, Jergens, Gibralter, etc. to hold two section firmly together. Like these: http://www.carrlane....A3C3B285351465C Obviously the hook would be rotated ninty degrees and used to pull against a stud mounted in the tie of the next section.


What's a good alloy for those aluminum joiners? Do you think he could bend up his own cantilever clamps from steel or stainless rod?
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#16 Onno Perdijk

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Posted 01 February 2009 - 07:14 PM

Hello Mike

Sorry that I did not get back sooner but I was a little blown away by the comment of Ira..

Wallthicknes: It al depends of the payload and the amount of crossties. I use 4mm but then they are being used for cranes over 2000kg. If you choose for roundtube you could decide to screw a U-profile underneath to give it more strength both vertical as horizontal (do not weld since that will change the structure of the aluminum which will decrease your straightness (correct english??)

Joints: This is the weakest (and most difficult) part of tracks. if you'd make them from aluminum or copper they will get sloppy very fast, even if you take very good care. If you can do it with stainlesssteel I really would recommend that. Glue them into your tubes by using a "filling-glue" like Loctite 603.

Crossties and spanners: Do not overspan your spanners since they will slightly bend your crossties which will make your trackgauge a little smaller (every 1/10 mm counts).... Spanners made out of aluminum will get sloppy very fast. Carbosteel can do the job very well.

Hope this helps,


Good Luck,

Onno Perdijk
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#17 JD Hartman

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Posted 02 February 2009 - 02:48 PM

6061 or 6065 alloy would be fine for the track joiners. Aluminum can even be hardened or anodized for added wear resistance. Or simply make them from low carbon steel bar. He's building the track for his own use, probably not to rent out. I've seen equipment get abused by crew on shoots, in this case it isn't likely to happen. Welding the crossties to the track doesn't change the physical makeup of the aluminum or weaken it. It will however make it harder to replace a damaged tie and if you're not adapt at welding, may cause warping in the metal. So I would mechanically fasten the channel used for the crossties to the track. The mechanics of the clamps I linked to have already been worked out. I doubt that you will save any money by trying to design and fabricate your own.
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#18 Mike Peters

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Posted 03 February 2009 - 03:38 PM

Thanks everyone for your suggestions

I'll post images of the finished track in a couple of weeks
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#19 Jonas Bendsen

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Posted 27 February 2012 - 12:44 PM

Thanks everyone for your suggestions

I'll post images of the finished track in a couple of weeks


I stumbled across this post (and joined the forums) looking for the standard width for dolly track.

I would add to the discussion: use galvanized steel pipe for your rails (8ft. pipe used for chain link fence). It's a bit heavier than aluminum, but it's much more sturdy (doesn't ding and bend) and it won't rust. You don't get the mess of oiling the track, and you don't need to mess with the considerable upkeep of painting.

Here is a link to my blog post on building a very affordable dolly with track.

Cheers.
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